\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing,decorations.pathreplacing,decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=latex,scale=0.75]
  \useasboundingbox(-2.1,-1.4)rectangle(3.65,3.7);
  \draw[double,double distance=2pt,rounded corners=6pt](0,2.0)--(0,2.6)--(2.5,2.6)--(2.5,1.6)(3.0,2.2)--(3.0,2.8);
  \draw[double=brown,double distance=3pt,rounded corners=6pt](2.0,2.6)--(2.5,2.6)--(2.5,2.1);
  \draw[double=darkgray,double distance=2pt](2.5,1.6)node[above left]{$B$}--(2.5,0)(3.0,2.2)node[above right]{$A$}--(3.0,0.6);
  
  \draw[very thin,<->](3.2,1.6)--(3.2,2.2)node[right,midway]{$h$};
  \draw[very thin, densely dashed] (2.5,1.6)--(3.3,1.6)(3.0,2.2)--(3.3,2.2);
  
  \draw[double=brown,double distance=3pt](2.5,0)--++(0,-0.2)arc(180:360:0.25)--++(0,0.8);
  \draw[left color=brown,right color=brown,middle color=lightgray](-0.18,1.8)--(-0.22,2.2)--(0.22,2.2)--(0.18,1.8)--cycle;
  \draw[fill=cyan!20,opacity=0.3](0,2.0)--(-0.25,2.0)arc(90:0:0.05)--(-0.2,1)..controls(-0.2,0.9)and(-0.2,0.7785)..(110:0.8)arc(110:430:0.8)..controls(0.2,0.7785)and(0.2,0.9)..(0.2,1)--(0.2,1.95)arc(180:90:0.05)--cycle;
  \draw[thin,->](3,3.2)--++(0,-0.4)node[at start,above]{$p_0$};
  \draw[fill=red](-1.7,0.7)circle(2pt);
  \draw[double=red,double distance=1pt](-1.7,0.7)--(-1.7,2.5);
  \draw[double=lightgray!10,double distance=1pt](-1.7,2.5)--(-1.7,3.0);
  \draw[double=black,double distance=1pt](-1.7,3.0)--(-1.7,3.1);
  \draw[fill=cyan!30,opacity=0.2,rounded corners=10pt](-2,1.7)--(-2,-1.3)--(2,-1.3)[sharp corners]--(2,1.7)--cycle;
  \draw[fill=cyan!20,opacity=0.2,rounded corners=10pt](-2,2.3)--(-2,-1.3)--(2,-1.3)--(2,2.3);
\end{tikzpicture}
\end{document}